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Original question:

PCM5121: Changing coefficient while in DAC running

PCM5121: Changing coefficient while in DAC running

na na78
Guru 16770 points
Part Number: PCM5121

Hi

The coefficient settings (writing C10 to C39) as soon as after setting normal operation (RQST=0) seems not to work, because it was no output.

However, if we take time about 21msec after setting RQST=0, we can see output after coefficient setting and mute released.

In both case, Mute is released after coefficient setting.

Should we have wait time after exiting Standby mode until starting normal operation?

BestRegards

  • 0
    TI__Genius 14220 points
    Hi,

    Thank you for your query. The responsible engineer for this part is not available at this moment due to holidays. He will get back to you soon.

    Regards,
    Applications Engineer, Precision DACs
  • 0 in reply to Uttam Sahu
    TI__Mastermind 46290 points
    Hello,

    The zero data detect functionality is carried out again when exiting stand-by mode. The approximate time required for zero data detection is shown in Table 6 on page 20 of the datasheet.
  • 0 in reply to Kevin Duke
    Guru 16770 points
    Hi Duke

    Thank you for your reply.

    I have question about zero data detect.
    Is it invalid for any CRAM access while zero data detect?

    Now, we can see the output with following procedure.

    1. stand-by mode(RQST=1)
    2. coefficient settings (Setting except for C10-C39)
    3. adaptive mode (AMDC=1)
    4. process flow setting (PSEL[4:0]=5)
    5. normal mode (RQST=0)
    >wait 21msec
    6. Coefficent settings (Setting C10-C39)

    I could not understand the necessary of wait time between 5 and 6.
    I thought even if procedure 6 is issued after procedure 5 soon, CRAM could be written.
    Is it not correct?

    BestRegards
  • 0 in reply to na na78
    Guru 16770 points
    Hi

    Could I have your view?
    I appreciate if you could reply.

    BestRegards
  • 0 in reply to na na78
    TI__Mastermind 46290 points
    Hello,

    I am currently out of office on business travel but Paul should be able to look into your topic in the next 24 hours in my place.

    Thank you for your patience.
  • 0 in reply to Kevin Duke
    TI__Guru 52663 points
    Hi Usui-san,

    I think the root of the issue is that you are trying to write to coefficients when the device is out of standby mode. Are you trying to write the Coefficients C10-39 to CRAMB and the other coefficients (all except C10-39) to CRAMA? Why are you waiting to exit standby before writing the coefficients?

    Thanks!
    Paul
  • 0 in reply to Paul_Frost
    Guru 16770 points
    Hi Frost-san

    I'm sorry for late reply.

    The customer intends to power up the device as fast as possible.

    Setting C10-C39 depends on user, so it could be set while in normal mode.

    The customer wants to avoid to set C10-C39 doubly before and after exiting standby mode.
    (It could be OK only to set C10-C39 with the device in normal mode.)

    So I want to confirm if writing CRAM is prohibited while zero data detection.

    BestRegards
  • 0 in reply to na na78
    Guru 16770 points
    Hi

    I appreciate if you could reply for following consideration.

    >So I want to confirm if writing CRAM is prohibited while zero data detection.

    Can you give us your view?

    BestRegards
  • 0 in reply to na na78
    TI__Guru 52663 points
    Hi Usui-san,

    Sorry for the delay. It is possible to set the CRAM coefficients in zero data detection, but remember that you can only write to the CRAM that is not being used by the DSP. For example, if the device is in adaptive mode you can write to CRAMB if CRAMA is being used by the DSP.

    Thanks!
    Paul
  • 0 in reply to Paul_Frost
    Guru 16770 points
    Hi Frost-san

    Thank you for your reply.

    I'm sorry I have not understood behavior of device yet.

    The following is successful operation.

    1. stand-by mode(RQST=1)
    2. coefficient settings (Setting except for C10-C39)
    3. adaptive mode (AMDC=1)
    4. process flow setting (PSEL[4:0]=5)
    5. normal mode (RQST=0)
    >wait 21msec
    6. Coefficent settings (Setting C10-C39)
    7. Unmute -> Output! Expected operation.


    On the other hands, following is failed operation.

    1. stand-by mode(RQST=1)
    2. coefficient settings (Setting except for C10-C39)
    3. adaptive mode (AMDC=1)
    4. process flow setting (PSEL[4:0]=5)
    5. normal mode (RQST=0)
    6. Coefficent settings (Setting C10-C39)
    7. Unmute -> No output!

    Differences between two operation is only wait time.
    So, the customer concerns if there is time interval to switch from Standby-mode to Normal-operation.



    BestRegards
  • 0 in reply to na na78
    Guru 16770 points
    Hi Frost-san

    Is it possible to give me your thought?
    >So, the customer concerns if there is time interval to switch from Standby-mode to Normal-operation.

    BestRegards
  • 0 in reply to na na78
    TI__Guru 52663 points
    Hi Usui-san,

    Sorry for the delay, I am looking in to this now.

    Thanks!
  • 0 in reply to Paul_Frost
    TI__Guru 52663 points
    Hi Usui-san,

    I have not been able to recreate what you are seeing. If I attempt to write to the coefficients (CRAM) after exiting standby, the device does not output - regardless of wait time. Do you have .cfg file for the configuration you are trying? My understanding of the device is that neither of the two scenarios you have described is valid, as you cannot right to the coefficients when the device is not in standby mode. Have you confirmed that in the case where the device outputs audio (21ms delay) that the desired process flow is fully implemented? It is possible that the default values in the C10-39 registers is enough for the DSP to operate, but not exhibit the desired features.

    Thanks!
    Paul
  • 0 in reply to Paul_Frost
    Guru 16770 points
    Hi Frost-san

    Thank you for your reply.
    Considering your comment, I want to mention CRAM state in each step.

    >1. stand-by mode(RQST=1)
    >2. coefficient settings (Setting except for C10-C39)
    >3. adaptive mode (AMDC=1)
    >4. process flow setting (PSEL[4:0]=5)
    >5. normal mode (RQST=0)
    >6. Coefficent settings (Setting C10-C39)


    1. CRAM(A+B) has default value (reset value).
    2. CRAM(A+B) is set by customer except for C10-C39. (However, C10-C39 have default value).
    3. Adaptive mode set
    4. Process flow set
    5. Same as step 4
    6. C10-C39 is attempted to accessed from I2C, however, it is impossible because DSP is using CRAMA.

    At step6, it is possible for DSP to work, but it would be in unexpected operation with unexpected (default) C10-C39.

    So if user could operate DSP as intended, he needs additional steps.

    7. Switch accessible CRAM from CRAMB to CRAMA. (DSP uses CRAMB)
    8. Customer can write coefficient to C10-C39 in CRAMA.
    9. And then, he should return CRAM from CRAMB to CRAMA for DSP.

    Step 7- 9 are processed in adaptive mode.

    It is my understanding. Could you please check it?

    BestRegards
  • 0 in reply to na na78
    TI__Guru 52663 points
    Hi Usui-san,

    Sorry for the delay. Your understanding is correct. Though note that without all coefficients being programmed the process flows behavior is undefined, so you may want write all the coefficients to the CRAM (A or B) exiting standby mode.

    Thanks!
  • 0 in reply to Paul_Frost
    Guru 16770 points
    Hi Frost-san

    Thank you for your reply.

    Let me close this thread once because the customer's response has stopped.

    I will open related thread if additional question has come up.

    Thank you.

    BestRegards